Railway track circuit apparatus



May 19, 1936. H" D. A ERNE'EHY RAILWAY TRACK CIRCUIT APPARATUS Filed Oct. 3,

\ INVENTOR Harry 0. Abernethy BY Q22 HIS ATTORNEY Patented May 19, 1936 UNITED STATES PATENT OFFICE 2,040,969 RAILWAY TRACK CIRCUIT APPARATUS Harry D. Abernethy, Lakewood, Ohio Application October 3, 1934, Serial No. 746,689

8 Claims.

My invention relates to railway track circuit apparatus, and has for an object the provision, in apparatus of this type, of a track circuit including a relay which will respond in one way to the 5 decrease of track voltage when a train enters the associated section, and in another way to the increase of track voltage when a. train leaves the section, but which will not be affected by steady values of track voltage or by gradual changes occurring therein due, for example, to changes in ballast conditions. 7

I will describe two forms of apparatus embodying my invention, and will then point out the novel features thereof in claims.

In the accompanying drawing, Fig.1 is a diagrammatic view showing one form of apparatus embodying my invention. Fig. 2 is a View showing a modification of a portion of the apparatus shown in Fig. 1 and also embodying my invention.

Similar reference characters refer to similar parts in each of the views.

Referring first to Fig. 1, the reference characters I and I designate the track rails of a stretch of railway track along which traffic normally moves in the direction indicated by the arrow. These rails are divided by insulated joints 2 to form a plurality of track sections of which only one complete section DE is shown in the drawing. Traffic moving through section DE from left to right is governed by a signal S which, as here shown, is a light signal comprising a proceed lamp G, a caution lamp Y, and a stop lamp R.

Section DE is provided with a track circuit comprising a battery H connected through a current limiting resistor Q across the rails at the exit end of the section, as well as the operating winding 3 of a track relay T connected across the rails at the entering end of the section. Winding 3 is mounted on a magnetizable core 4 which also carries the inductively coupled winding 5. Winding 5 supplies energy for pole-changing the lastposition polar relay A.

Relay A is a polar relay of suitable construction such that when current of normal relative polarity is supplied to its operating winding, the armature 6 will be swung to the normal or lefthand position, closing normal contacts 1-8 and 9-43; and when the operating winding is supplied with current of reverse relative polarity, the armature will be swung to the reverse or righthand position, closing reverse contact ll I. It will be understood that armature 6 will remain in the last operated position until an impulse of current'of the proper polarity for reversing the armature is induced in winding 5. The insulation 22 serves to insulate the normal contacts 1--8 and 923 from each other.

Associated with relays T and A is a distant relay K which is energized from a suitable source of current having the terminals B-C, over the normal contact 9-23 of relay K at location B, as. well as over the front contact I2 of relay T, also at location B, and line wire l5.

The proceed lamp G is provided with a circuit which passes from terminal B, through the front point of contact l3 of relay T, normal contact |-8 of relay A, front point of contact [4 of relay K, and lamp G to terminal C of the same source of current. The caution lamp Y is provided with a circuit which passes from terminal B, through the front point of contact 13 of relay T, normal contact 18 of relay A, back point of contact M of relay K, and lamp Y to terminal C; The stop lamp R is provided with two circuits, One of these extends from terminal B through the reverse contact l0-H of relay A, and lamp R to terminal C; the other extends from terminal B through the back point of contact l3 of relay T, and lamp R to terminal C.

The operation of the system is as follows 2' When section DE is unoccupied, relay T is energized by current from battery H, and armature 6 of relay A is in the normal position as shown in the drawing. If the section next in advance is also unoccupied, relay K is energized. Lamp G will then be lighted so that signal S will indicate proceed. If, however, the section in advance of location E is occupied by a train, relay K Will be deenergized, so that lamp Y will be lighted and signal S will indicate caution.

I will now assume that a train enters section DE. When this occurs, the shunt afforded by the wheels and axles of the train will suddenly reduce the amount of current flowing in winding 3 of relay T and this rapid change in the current will induce a current impulse in winding 5, of such polarity as to reverse the position of armature 6. This armature will then remain in its reverse position because relay A is characterized by the fact that when it becomes deenergized, the armature remains in the position corresponding to the polarity of the current with which the relay was last energized. If the shunt aiTorded by the wheels and axles of the train is sufficiently effective, the current supplied to relay T will be reduced below the release point of the relay, and this relay will accordingly operate to open its front contacts and to close its back contact. If, however, the current supplied to winding 3 is not reduced to the release point of relay T,

' this relay will remain energized. In either event,

the circuit for the proceed lamp G as well as for the lamp Ywill be opened at normal contact 1-8 of relay A, and if'relay T releases, this circuit will also be opened at the front point of contact 13 of relay T. The first circuit for stop lamp R will be closed at reverse contact |l I of relay A, and if relay T releases, the second circuit for lamp R will be closed at the back point of contact l3 of this relay. Signal S will then indicate stop.

When the train leaves section DE'there will be a sudden increase in the amount of current supplied to winding 30f relay T, andjhis rapid' change in current will cause an'impulse to be induced in winding of such polarity as to return the-armature ,6 to its normal orleft-handposition. This armature will thereafter remainin its normal position until the relay again becomes energized by an impulse of reverse polarity. If"

relay T became deene'rgiized while the train'was in the section, this relay will now again become energized. Relay K will have become deener- 'gized due to; the train entering the section in ad- Vance of section D'E, and so signal S will indicate caution'until the'train passes out 'of the advance section, when itf will again indicate proceed.

s 1 The operation of relaylA is independent of the track energy level at tl'ieleft-hand end'of the section DEf'and is dependent only on the change in the amount of current supplied to winding 3 or reia'y T, that is, to a change in track voltage'occurringwhen a train enters or leaves th'sec'ti-On. i It' follows, therefore, that changes in the characteristics of the track circuit due to variations in weather or other conditions will not affect the operation of this relay. During dry weather conditions when very good shunting action is necessary to causerelay T to'release in response to attain entering the section, relay A will be reversed by a relativ'elypoor shunt because of the relatively large change in the amount of currnt'supplied to winding 3 which occurs as thefexception that a thermal relay provided f or rendering the operation of the system somewhat more positive." It will 'be noted that in Fig. 2 the energizing circuit for winding 3 of relay T normall'y includes the normal contact ll-Qlll of relay A. In parallel with the normally closed contact I'|- I8 is the normally open contact [9 -20 of the thermal relay TR: This latterconta'ct becomes closed upon the lapse of a predetermined time interval following the release of relay T and the resultant closingof back contactlli, which completes" the energizing circuit for the'heating winding 2Iof relay TR. J

-'I 'he operation of the system of Fig. 2 is as follows: When a train enters section D E, the

1 sudden decrease of current in winding 3 'will cause armature 6 'of relay A to reverse, opening norrrialcontact .ll l8 which opens'the circuit of the operating winding 3 of relay T. Thus it becomes apparent that not only does the train shunt initially decrease the energizing current of the track relay T,but as soon as a reversal of relay Aoccurs, relay T is placed on open circuit,

winding 2| of the thermal relay TR will become 7 closed at back contact l6 of relay T.

After a predetermined time interval following the closing of contact l6, contact l92|l' of relay 'I'R'will close, thus completing the circuit for winding 3 of relay T. If the train has passed out of thesection DE prior to the closingof contact I9- -20, winding 3 of relay T will immedi-' ately receive a rush of current which will restore armature 6 of relay A to its normal position, and

which will cause'relay T to pickup. Assuming that the train still occupies the section'next in advance of section DE, signal S will indicate caution, lamp Y being lighted over the same circuit 'traced for this lamp in connection with Fig. 1. Similarly, if the train has passed out of the section next inadvance of section DE, signal S will indicate proceed. T l Should the train still occupy section D--E at the time when contact l9'20 of relay TR becomes closed, .neither relayA nor relay T will operate, forobvious reasons, until such time as the train leaves the section, 'It will be. apparent from the 'foregoing that the thermal relay TR in conjunction with the contact l|l8 of relay 'A provides for a more positive release of relay T,

impossible for sudden whereby it becomes changes in track voltage occasioned, for example, by intermittent shunting or other causes to operate either relay T or A prior tothe expiration of the time interval of relayTR. In this manner, positive shunting is enforced and signal fiips are avoided. It will be apparent that any suitable timeelement relay may be used in place of the thermal relay TR. r Although I haveherein shown and described only two forms of apparatus embodying my invention, it is understood that various changes and modifications may be made'therein within the scope of the appended claims without de;- parting fromthe spirit and scope of my invention.

Having thus described my invention, 'what I claim is:

' 1. In combination with a section of railway track and a source of current connected across the rails of said section, a main relay having'an operating winding receiving current from 1 said.

relay and said auxiliary relay and selectively responsive to the position assumed by said auxiliary relay.

2. In combination with a section of railway track and a source of current connected across the rails of said section, a main relayhaving a first winding receiving current from said rails for operating the relay and having a second winding inductively coupled with said first wind ing, a polarized'auxiliary relay receiving current from said second winding and capable of assum ing a normal or a reverse position according as the current received by said first winding israpidly decreased when a train enters the section or is rapidly increased when a train leaves the section, and signaling apparatus controlled by both said main relay and said auxiliary relay and selectively responsive to the position assumed by said auxiliary relay.

3. In combination, two successive sections of railway track, a source of current connected across the rails of each section, a main relay for each section having an operating winding receiving current from the rails of the section, a polarized auxiliary relay for the rear section receiving current by induction from the operating winding of the main relay for said rear section and capable of assuming a normal or a reverse position according as the current received by said operating winding is rapidly decreased when a train enters the associated section or is rapidly increased when a train leaves the associated section, a distant relay for the rear section controlled by the main relay of the forward section, and signaling apparatus for said rear section controlled by said polarized relay and said distant relay.

4. In combination, two successive sections of railway track, a source of current connected across the rails of each section, a main relay for each section having an operating winding receiving current from the rails of the section, a polarized auxiliary relay for the rear section receiving current by induction from the operating winding of the main relay for said rear section and capable of assuming a normal or a reverse position according as the current received by said operating winding is rapidly decreased when a train enters the associated section or is rapidly increased when a train leaves the associated section, a distant relay for the rear section controlled by the main relay of the forward section; and signaling apparatus for said rear section controlled over a contact of the main relay for the rear, section, a normal contact of said polarized relay, and a contact of said distant relay.

5. In combination, two successive sections of railway track, a source of current connected across the rails of each section, a main relay for each section having an operating winding receiving current from the rails of the section, a polarized auxiliary relay for the'rear section receiving current by induction from the operating winding of the main relay for said rear section and capable of assuming a normal or a reverse position according as the current received by said operating winding is rapidly decreased when a train enters the associated section or is rapidly increased when a train leaves the associated section, a distant relay for the rear section controlled by the main relay of the forward section, a signal for said rear section; a proceed circuit for said signal including a front contact of the main relay for the rear section, a normal contact of said polarized relay, and a front contact of said distant relay; a caution circuit for said signal including said front contact of the main relay, said normal contact of the polarized relay, and a back contact of said distant relay; and a stop circuit for said signal including a back contact of the main relay for said rear section.

6. In combination, two successive sections of railway track, a source of current connected across the rails of each section, a main relay for each section having an operating winding receiving current from the rails of the section, a polarized auxiliary relay for each section receiving current by induction from the operating winding of the main relay associated therewith and capable of assuming a normal tor a-reverse position according as the current received by said operating winding is rapidly decreased when a train enters the associated section or is rapidly increased when a train leaves the associated section, a distant relay for the rear section controlled by the main relay for the forward section as well as by the polarized relay for said forward section; and signaling apparatus for said rear section controlled by the main relay, the polarized relay, and the distant relay, all associated with said rear section.

'7. In combination with a section of railway track and a source of current connected across the rails of said section, a main relay having an operating winding normally receiving current from said rails, a polarized auxiliary relay receiving current by induction from said operating winding and capable of assuming a normal or a reverse position according as the current received by said operating winding is rapidly de--' creased when a train enters the section or is rapidly increased when a train leaves the section, a normal contact of said polarized relay included in the circuit for said operating Winding, time element means effective when said main relay is deenergized for closing a path around said normal contact after the lapse of a predetermined time interval whereby the circuit for said operating winding becomes closed, and signaling apparatus controlled by said main relay.

8. In combination with a section of railway track and a source of current connected across the rails of said section, a main relay having an operating winding normally receiving current from said rails, a polarized auxiliary relay receiving current by induction from said. operating winding and capable of assuming a normal or a reverse position according as the current received by said operating winding is rapidly decreased when a train enters the section or is rapidly increased when a train leaves the section, a normal contact of said polarized relay included in the circuit for said operating winding, a thermal relay controlled over a back contact of said main relay, means governed by said thermal relay for shunting out said normal contact after the lapse of a predetermined time interval following the deenergization of said main relay, and signaling apparatus controlled by said main relay and said polarized relay.

HARRY D. ABERNETHY. 

